The disclosure relates generally to fluid turbine blades and more particularly, to a fluid turbine blade including decoupled structural stiffness and torsionally compliant segmented non-structural skin.
Commonly, fluid turbines are employed to generate electricity from kinetic energy of fluids. Two non-limiting turbine examples include wind energy and marine hydrokinetic energy turbines. Such turbines include three major components: a structural support component, a generator component and a rotor component. The rotor component further includes turbine blades that are employed to convert the kinetic energy of fluid to a mechanical energy. Furthermore, the mechanical energy is converted to electricity with the help of the generator component.
Typically, wind turbine blades, for example, include a rectangular or I-shaped spar disposed along a span of the wind turbine blade. The spar carries a major portion of a load induced by the kinetic energy of the wind on the wind turbine blade. The load is directed at an angle on the wind turbine blade and results in a multiaxial loading of the rectangular or I-shaped spar. The multiaxial state of loading including flapwise bending, edgewise bending and torsion, induces warping of the rectangular or I-shaped spar and results in higher stresses in the rectangular or I-shaped spar. Therefore, the multiaxial state of loading leads to an inefficient design and excess material utilization. The excess material utilization results in a heavier wind turbine blade. Furthermore, the inefficient design increases the maintenance cost and reduces life of the wind turbine blade.
Advanced aeroelastic axial-twist coupling is seen as a way to shed the multiaxial load and a control mechanism. The wind turbine blades with rectangular or I-beam spars are not conducive for inducing the axial twist coupling and result in a more complicated aerodynamic shape to achieve axial twist coupling. The complicated shapes lead to increased cost of manufacturing and design complexity.
New wind blade designs incorporating enhanced twist properties enable load shedding, thereby producing a reduction in loads. The lower loads allow the length of the blade to be increased resulting in larger annualized energy production (AEP). Due to the increased twist in blades of this design, buckling of the outer skin may occur when under the effects of aerodynamic pressure.
Hence, there is a need for an improved fluid turbine blade design to address one or more aforementioned issues.